Plectopylis cairnsi Gude, 1898

Páll-Gergely, Barna, 2018, Systematic revision of the Plectopylinae (Gastropoda, Pulmonata, Plectopylidae), European Journal of Taxonomy 455, pp. 1-114 : 85-89

Plectopylis cairnsi Gude, 1898

Figs 34 B–C, 35D–F, 38C–D, 39

Plectopylis cairnsi Gude 1898g: 171 . fig. 90 a–g [“possibly Burma ”].

Plectopylis (Plectopylis) cairnsi – Gude 1899d: 148; 1899e: 175; 1914b: 129–130, fig. 64a–g. Plectopylis achatina – Boonngam et al. 2008: 259, fig. 2.

Diagnosis

A large, sinistral species with an apertural fold that is not in contact with the lambda-complex.

Material examined

Holotype

MYANMAR: 1 shell, holotype, Burma ? ( NHMUK 1922.8.29.47).

Additional material

THAILAND: 14 shells, Krabi Province, Limestone Ridge on E side of Highway 4.9 km NW of Krabi, 8°11′ N, 98°51′ E, 40 m a.s.l., 25 Sept. 1985, F.G. Thompson leg. ( UF 76744); 3 shells, same data as for preceding ( HNHM 97479); 16 specimens (preserved in ethanol), same data as for preceding ( UF 76457); 7 shells, Krabi Province, S side of Limestone Ridge, 6.4 km ENE of Ban Chong Phli, 8°05′ N, 98°51′ E, 26 Sep. 1985, F.G. Thompson leg. ( UF 76787); 197 shells, Krabi Province, Limestone Ridge 6 km Ne, 2.5 km N of Krabi, 8°07′ N, 98°56′ E, 100 m a.s.l., 26 Sep. 1985, F.G. Thompson leg. ( UF 76761); 20 specimens (preserved in ethanol: two of them, PL011 and PL012, used for molecular study) ( UF 76467); 6 shells (mixed sample with P. thompsoni sp. nov.), Krabi Province, 10 km NE of Ao Luk, 8°29′ N, 98°49′ E, 30 Sep. 1985, F.G. Thompson leg. ( UF 77252); 2 specimens (preserved in ethanol: PL015 and PL016 used for molecular study), same data as for preceding ( UF 77252); 2 shells, Krabi Province, limestone knoll on the W side of Highway 401, 2.2 km N of Ban Ao Luk Nua, 8°25′ N, 98°44′ E, 25 Sep. 1985, F.G. Thompson leg. ( UF 76723); 3 shells, Krabi Province, Wat Tham Sua, Nation Valley, Mar. 2000, J. and Ch. Hemmen leg. (coll. PGB); 3 shells, Krabi Province, ca 2.5 km W of Nong Khon, road nr 4033 (NW of Krabi), Oct. 1999, J. and Ch. Hemmen leg. ( HNHM 97480); 12 shells, same data as for preceding (coll. PGB); 3 shells, Krabi Province, ca 0.3 km SE of Bau Chong Phili (NW of Krabi), Oct. 1999, J. and Ch. Hemmen leg. (coll. PGB); 5 shells, Krabi Province, off Km 117.6, road # 4 (Phang Nga–Krabi), 1.5 km on unpaved road, 8°09.574′ N, 98°51.761′ E, Sep. 2000, J. and Ch. Hemmen leg. (coll. PGB); 5 shells, Krabi Province, Khao Phung Cave Forest Park (ca 20 km N of Krabi), 3 Mar. 2000, J. and Ch. Hemmen leg. (coll. PGB); 2 shells, Krabi Province, left side off Km 23, # no. 4, Phang Nga- Krabi, Mar. 2000, J. and Ch. Hemmen leg.(coll. PGB); 10 shells, Krabi Province, WNW of Amphoe Khao Phanom (from rd # 4037 to rd # 4) limestone hill at left side, 8°22.711′ N, 98°56.183′ E, J. and Ch. Hemmen leg. (coll. PGB); 6 shells, Krabi Province, ca 6 km N of Ban Nai Sa (NW of Krabi), Mar. 2000, J. and Ch. Hemmen leg. (coll. PGB); 3 shells, Krabi Province, Kao Klom, (NW of Krabi), Oct. 1999, J. and Ch. Hemmen leg. (coll. PGB); 2 shells, Krabi Province, canyon ca 1.3 km W of road # 4, direction to old town of Ao Luk (Krabi to Phang Nga), 8°22.382′ N, 98°44.043′ E, J. and Ch. Hemmen leg. (coll. PGB); 6 shells, Krabi Province, limestone hill, left side off Km 112 road # 4 (Krabi–Phang Nga), 8°05.758′ N, 98°52.106′ E, 22 Oct. 2000, J. and Ch. Hemmen leg. (coll. PGB); 7 shells, Krabi Province, Wat Tham Sua, Nation Valley (near Krabi), 8°07.691′ N, 98°55.678′ E, Oct. 2000, J. and Ch. Hemmen leg. (coll. PGB); 7 shells, Krabi Province, North of Krabi, Tiger Cave Temple, Wort Tham Sena, 8°07′36.15″ N, 98°55′26.65″ E, Sep. 2007, A. Reischütz leg. (coll. REI); 1 shell, 1 damaged shell, (coll. PGB); 2 shells, Tiger Cave, Krabi (coll. PGB) (ex coll. K. Okubo); 9 shells, 4 tissue samples, 4 specimens in ethanol, Phangnga, Ao Nang, N side of cliff, 8°1.93′ N, 98°50.28′ E, 70 m a.s.l., 26 Jul. 2010, B. Hausdorf leg. ( ZMH 51951); 4 shells, 2 tissue samples, 3 specimens in ethanol, Krabi, Ban Chong Mai Kaeow, N of Ao Luek Nuea, calcareous rocks, 8°24.87′ N, 98°44.22′ E, 60 m a.s.l., 31 Jul. 2010, B. Hausdorf leg. ( ZMH 51964); 1 shell, Krabi, Phanom Benja National Park, Huai To waterfall and surrounding forest, 8°14.35′ N, 98°54.87′ E, 120 m a.s.l., 28 Jul. 2010, B. Hausdorf leg. ( ZMH 51992); 3 shells, Krabi, Thap Prik, calcareous rocks N of, 8°10.75′ N, 98°52.45′ E, 60 m a.s.l., 28 Jul. 2010, B. Hausdorf leg. ( ZMH 79010); 3 shells, Southern Thailand, Andaman Sea side, Krabi Province, Phnom Mountain, donated by Mr Somnuek Patamakanthin and Mr Samwang Patamakanthin, 31 Jul. 2006 ( NHMUK 2006.03.29).

Description

SHELL. Sinistral, almost flat, spire only slightly elevated; whorls 5.5; basal colour yellowish to greyish, dorsal surface with brownish-red and paler stripes; protoconch consists of 2.5–2.75 whorls, extremely finely granular with fine, irregular growth wrinkles; teleoconch very finely, regularly ribbed and decussated with fine spiral lines; sculpture less prominent on ventral side; peristome thickened and slightly reflected, with a rather weak, blunt parietal callus; apertural fold continuous with main plica, usually free from parietal callus (or reaches with a thinner projection).

Lambda-complex complete; upper branch and left leg elongated; main plica free from lambda-complex; short horizontal plica may be present under lambda-complex. Palatal wall typical of Plectopylis .

MEASUREMENTS (in mm). D = 18.9, H = 6.5 (holotype); D = 18.4–21.1, H = 6.3–7.4 (n = 3, shells from Thailand).

CHARACTERS OF THE GENITAL SYSTEM. One specimen from sample UF 76467 was examined. Left ommatophoral retractor runs between penis and vagina; penis relatively long, internally with parallel, serrate folds and tiny calcareous crystals; epiphallus and vas deferens attached to penis with weak muscle fibres; no penial caecum observed; epiphallus internally with three main, and some minor longitudinal folds; retractor muscle thick and inserts on proximal part of penis; vagina approx. half of length of penis, and of comparable diameter; bursa copulatrix with a very short, slender stalk, and a very long, elongate, thick bursa; diverticulum ovate, slightly shorter than stalk of bursa copulatrix; diverticulum contained a spermatophore, which is long, fragile, reddish brown tube folded multiple times, forming an ovate mass having pointed ends.

RADULA. Centrals with small, triangular cusps; endocones of laterals ovoid with pointed tip; ectocones of first laterals much larger than centrals; ectocones of marginals undivided, endocones of marginals mostly undivided.

Differential diagnosis

Plectopylis thompsoni sp. nov. is larger and flatter, the right leg of its lambda-complex is absent, and the main plica is connected to the lambda-complex. Plectopylis bensoni is usually larger, has a shouldered body whorl (more rounded in cairnsi ), and the main plica is connected to the lambda-complex (not connected in cairnsi ). For the differences with P. malayana sp. nov., see under that species.

Distribution

This species is known from Krabi Province in Thailand only. In one of the localities, Plectopylis cairnsi co-occurs with P. thompsoni sp. nov. ( Fig. 40 ).

Remarks

Most examined shells had the main plica and the apertural fold connected. In contrast, they are free from each other in the holotype of P. cairnsi . Furthermore, the main plica reaches the parietal callus in the holotype and only in the minority of the Thai shells. In view of these differences, which I consider minor, I do not find it necessary to treat the Thai populations as a distinct taxon.

Figures

Fig. 34. Shells of species of Plectopylis Benson, 1860. A. P. anguina (Gould, 1847), paralectotype (NHMUK 20140812). B. P. cairnsi Gude, 1898, holotype (NHMUK 1922.8.29.47). C. P. cairnsi (UF 76761). D. P. bensoni Gude, 1914, paralectotype of Helix repercussa Gould, 1856 (NHMUK 20140813). E. Neotype of P. bensoni (NHMUK 20170143). Scale bar = 10 mm. Photos: T. Deli (C), B. Páll-Gergely (E) and H. Taylor (A–B, D).

Fig. 40. Distribution of species of Plectopylis Benson, 1860 in Southern Thailand and northern Malaysia. Legends: empty triangle = P. thompsoni sp. nov.; square = P. cairnsi Gude, 1898; filled triangle = sympatric locality of P. thompsoni sp. nov. and P. cairnsi; circle = P. malayana sp. nov.